A variable intake system is typically configured to change the length of an intake passage extended to the combustion chamber according to the engine state. The variable intake system, therefore, lengthens the intake passage during a low speed and light load for increasing the intake inertia and intake efficiency. Conversely, during a high speed and heavy load, the variable intake system shortens the intake passage to increase the intake efficiency by decreasing the intake resistance.
Conventional variable intake systems change the passage of the intake through use of valves. However, if the valves fail to operate properly, significant amounts of toxic materials can accumulate in the engine exhaust gas and deteriorate engine performance. This in turn can require the time and expense of regular inspections of the valves.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement of any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.